Development of electrically conductive resins for DLP printing applications

Viktoria Feigl

Research output: ThesisMaster's Thesis

Abstract

Developing electrically conductive photopolymer composites and using them with digital light processing 3D printing for the additive manufacturing of multi-material structures could revolutionize the electronics industry in the near future. To approach this goal, electrically conductive polymers were prepared in this thesis by adding electrically conductive fillers. In the course of this, both, the base resin and the filler system were optimized. Due to their viscosities, suitable for incorporating filler, one epoxy and one acrylic resin were selected for the experiments. In the rheological measurements, it was found that processing at 50 °C gives clear advantages in terms of viscosity and the degree of filling that can be achieved. Dendritic copper particles together with carbon nanotubes were used as filler system. Although a higher concentration of filler facilitated a higher electrical conductivity, it also led to a stronger absorption of light and thus, to a decrease of the photochemical reaction kinetics. This was not only shown in photo-differential scanning calorimetry results, as the enthalpy decreased strongly, but also in 3D printing tests. Due to the reduction of the light penetration depth it was not possible to cure resin layers with higher layer thickness efficiently. It was also found that the electrical conductivity does not only depend on the filling degree but also on the matrix and the photoinitiator content. A higher concentration of photoinitiator gave better electrical conductivities but could also bring a positive effect on the photopolymerization rate and the printing time. During all experiments, the selected epoxide resin and the acrylate system were compared as a matrix and the same conclusion was found several times. The acrylate resin, due to its higher reactivity in radical-mediated photopolymerization, led to a faster and more exothermic reaction, less required energy for curing and higher electrical conductivity of the cured materials. With this research, a foundation for future studies could be laid and essential information on achievable filler concentrations with the resins used could be obtained.
Translated title of the contributionEntwicklung von elektrisch leitfähigen Harzsystemen für DLP Druckanwendungen
Original languageEnglish
QualificationDipl.-Ing.
Awarding Institution
  • Montanuniversität
Supervisors/Advisors
  • Rossegger, Elisabeth, Supervisor (external)
  • Schlögl, Sandra, Supervisor (internal)
Award date30 Jun 2023
Publication statusPublished - 2023

Bibliographical note

embargoed until 25-05-2028

Keywords

  • 3D printing
  • DLP
  • Digital Light Processing
  • multimaterial printing
  • electrically conductive fillers
  • dendritic copper particles
  • CNT
  • electrically conductive composite
  • electrically conductive resin
  • photopolymerization
  • resin-filler-system
  • photoreactivity
  • UV light shielding
  • printability

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